Beamlines of the biomedical imaging and therapy facility at the Canadian light source—Part 1

doi:10.1016/j.nima.2007.08.087

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

Volume 582, Issue 1, 11 November 2007, Pages 73-76

https://doi.org/10.1016/j.nima.2007.08.087 Get rights and content

Abstract

The BioMedical Imaging and Therapy (BMIT) Facility will provide synchrotron-specific imaging and therapy capabilities. This paper describes one of the BMIT beamlines: the bend magnet (BM) beamline 05B1-1. It plays a complementary role to the insertion device (ID) beamline 051D-2 and allows either monochromatic or filtered white beam to be used in the experimental hutch. The monochromatic spectral range will span 8–40 keV, and the beam is more than 200 mm wide in the experimental hutch for imaging studies of small and medium-size animals (up to sheep size). The experimental hutch will have a positioning system that will allow imaging (computed tomography and planar imaging) as well as radiation therapy applications with both filtered white and monochromatic X-ray beams and will handle subjects up to 120 kg. Several different focal plane detectors (cameras) will be available with resolutions ranging from 10 to 150 μm.

Introduction

The Biomedical Imaging and Therapy (BMIT) laboratory will provide unique synchrotron-specific X-ray imaging and therapy capabilities [1]. The BMIT design implements many lessons learned at other institutions (SSRL [2], NSLS [3], DESY [4] and ESRF [5]). It will be used to address unsolved problems in medicine (human and animal), agriculture, and other biomedical sciences [6]. The BMIT facility is accessed for experiments in two hutches, POE-2 and SOE-1 (Fig. 1).

The BM beamline shares POE-2 with the ID beamline for experiments [7] when the ID beamline is in therapy mode. One advantage is that it will be possible to quickly move the subject between the BM and ID beams in POE-2 for imaging and therapy. The BM beamline has exclusive use of POE-2 when the ID beamline is in imaging mode in SOE-1.

The bend magnet beamline is intended to be used for testing new ideas in imaging and therapy and to validate techniques for eventual translation to the insertion device beamline. The bend magnet will, however, mirror some of the ID capabilities with absorption imaging, DEI and phase contrast in both CT and planar modes [6]. Additionally, the bend magnet will host new imaging methods, such as imaging based on structural aspects of tissues by diffraction, absorption spectroscopy imaging, fluorescence imaging, and others. Such tissue characterization methods may form the basis of programs that will translate to the ID beamline or even to clinical settings.

Section snippets

Source

The bend magnet front end is typical of many CLS beamlines [8], [9]. The maximum horizontal photon beam angle is 19.54 mrad of which the BM beamline utilizes 10 mrad. The optics hutch allows both monochromatized beam and filtered white beam to be used in the experimental hutch. The monochromator will prepare a beam-width in excess of 200 mm in the experimental hutch with an energy range (8–40 keV) appropriate for imaging studies in small and medium-size animals (up to sheep size) systems. The

POE-1 (optics hutch)

The main components within the optics hutch are shown in Fig. 3: fixed mask (a), primary photon slits (b), filter assembly (c), wire beam positioning monitor (d), monochromator (e), secondary photon slits (f), fluorescent view screen (g), photon shutter (h), fast shutter for imaging (i), safety shutter (j) and wall collimator (k). The vacuum section of POE-1 is isolated from air ambient by the last component, the Be/Al window located in POE-2 [11].

POE-2 (experimental hutch)

The experimental hutch (Fig. 4) has one fixed component: beam stop (d) at the backwall. All other components are moveable to allow for versatility in experimental setup. Every experiment would utilize at the minimum an optics table (a) in front of the hutch that will hold additional shutters, collimators as well as ion chambers and other optical components. Next is the positioning system. For the large samples we plan to use the same positioning system that is used on the ID line (b)—capable of

Conclusions and discussion

The BMIT bend magnet beamline will provide a testing ground for many of the ID components including monochromators and cameras, a place to develop new imaging technologies, and secondary capacity for imaging experiments from the wiggler device beamline as well as offloading some of the imaging research from the ID beamline.

Acknowledgments

This project is supported by an Infrastructure Grant from the Canada Foundation for Innovation, the Province of Saskatchewan and more than 19 other private and public granting agencies.

References (11)

W.C. Thomlinson
Nucl. Instrum. Meth. Phys. Res. A
(2005)
H. Elleaume et al.
Nucl. Instrum. Meth. Phys. Res. A
(1999)
E. Rubenstein et al.
Trans. Am. Clin. Climatol. Assoc.
(1985)
W. Thomlinson et al.
Rev. Sci. Instrum.
(1992)
W.R. Dix et al.
J. Synchrot. Rad.
(2003)

There are more references available in the full text version of this article.

Cited by (104)

W. A. Barletta and his interests in the synchrotron radiation science
2024, Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
Resolving mass transport losses at the catalyst layer of polymer electrolyte membrane fuel cells through semi-empirical modelling
2023, Electrochimica Acta
In this study, the sources of oxygen transport resistance in a polymer electrolyte membrane (PEM) fuel cell are resolved using two different approaches: pore network modelling and empirical modelling. This is achieved by applying operando imaging and electrochemical performance testing results to the pore network model and empirical model, respectively. In the literature, the impact of liquid water on oxygen transport resistance in a 5-layer membrane electrode assembly is typically attributed to the accumulation of liquid water within the gas diffusion layer. A comparison of the oxygen transport resistance values predicted by pore network modelling to the values predicted by empirical modelling shows that empirical models significantly overpredict the contribution of the substrate within gas diffusion layers to oxygen transport resistance at limiting current conditions (up to 440%). Statistical analysis of the discrepancy (residual) between the values of the oxygen transport resistance of the substrate predicted by the empirical and pore network models indicates that the residual can be attributed to oxygen transport resistance in locations that are related to water production but independent of the relative humidity of the inlet: the catalyst layer (CL) and/or CL-microporous layer interface.
Temperature enhances the ohmic and mass transport behaviour in membrane electrode assembly carbon dioxide electrolyzers
2021, Energy Conversion and Management
The operating temperature is a critical parameter for improving the performance of a carbon dioxide electrolyzer. Specifically, the power density reduced by up to 35% (at 215 mA/cm²) when increasing the operating temperature from 25 °C to 60 °C, and increasing the cell temperature led to significantly lower ohmic resistances and mass transport limitations. A 5–fold reduction in ohmic resistance (from 3.35 Ω·cm² to 0.64 Ω·cm²) was achieved by increasing the cell temperature from 25 °C to 60 °C at 215 mA/cm². These reductions in ohmic overvoltages were attributed to higher cation exchange membrane water content at higher operating temperatures observed via synchrotron X-ray radiography. The higher water content at higher temperatures was attributed to the relaxation of the polymer backbone of the membrane. The dominating mechanisms for mass transport limitations at high current densities (≥305 mA/cm²) were temperature dependent. Specifically, at 40 °C, liquid water in the electrode inhibited reactant carbon dioxide transport to the reaction sites; whereas, at 60 °C, the product gas saturation in the electrode inhibited mass transport. However, a higher temperature led to consistently lower mass transport losses at each current density (e.g., a reduction from 0.75 V to 0.37 V at 395 mA/cm² when increasing the temperature from 40 °C to 60 °C) since less water accumulated in the cathode gas diffusion layer.
Imaging of desaturation of the frozen gas diffusion layers by synchrotron X-ray radiography
2021, International Journal of Hydrogen Energy
The visualization of the thawing and desaturation process on an initially saturated, frozen gas diffusion layer (GDL) with a serpentine gas flow channel was performed based on synchrotron X-ray computed tomography images. High speed CT scanning during the experiments allowed the dynamic desaturation process to be quantified under the cold-start with air purging condition. The saturation profiles and the desaturation rates were studied over the entire GDL domain, through-plane, and in selected regions of interest for localized behavior. Sigracet 35AA and 35BA GDLs were selected for the experiments to study the effects of GDL hydrophobicity. Along with the real-time saturation profiles, the average desaturation rates for the entire GDL domain over the whole purging process were 0.000186 μL cm⁻² s⁻¹, 0.000470 μL cm⁻² s⁻¹, 0.000516 μL cm⁻² s⁻¹ and 0.000901 μL cm⁻² s⁻¹ with the superficial gas velocity of the purging air at 2.88 m/s, 4.26 m/s, 5.98 m/s and 9.02 m/s, respectively. In addition, the dynamic saturation contours and 3-D GDL geometry models were constructed to show the liquid water movement through a GDL. Although the GDL desaturation curves for each experiment share similar trends, the results show that different conditions including air flow rate, GDL geometric location, initial water saturation, and GDL boundary condition could cause heterogeneous desaturation behavior on both overall and localized GDL regions. These data provide valuable information for future modeling studies that involve the thawing process in the GDL, and could be used to optimize the cell design and develop cold-start protocols.
Resolving the gas diffusion layer substrate land and channel region contributions to the oxygen transport resistance of a partially-saturated substrate
2019, Electrochimica Acta
A novel analytical model was derived for the first time to predict the substrate oxygen transport resistance as a function of local saturations in the substrate region under the channel (region C) and the substrate region under the land (region L). Prior to this work, the state-of-the-art was limited to correlating bulk substrate oxygen transport resistance to bulk liquid water saturation in the GDL substrate. In this work, a semi-empirical approach was taken whereby the exponents m and n for calculating the effective diffusivity and the effective diffusion distance in region L were determined through a calibration process with experimentally measured saturations and calculated substrate oxygen transport resistance. The distinct relationships between local saturation and effective diffusivity for region C and region L were elucidated from the model. Via the model, it was determined that the local saturation in region C had an up to 2.8 times higher impact on the substrate oxygen transport resistance than the local saturation in region L. The oxygen transport resistance analysis was further supported by experimentally measured mass transport resistance of the fuel cell. The rise of saturation in region C led to a significant increase in the mass transport resistance; in contrast, increasing saturation in region L had a relatively lower impact on the mass transport resistance.
Microstructural and mechanical characterization of variability in porous advanced ceramics using X-ray computed tomography and digital image correlation
2019, Materials Characterization
This paper explores microstructural and mechanical variability in porous ceramics, combining advanced X-ray computed tomography (XCT) and digital image correlation (DIC) techniques to characterize an alumina material. The results show low variability in microstructure, with median pore size values for this alumina ranging from 16.0 μm to 17.2 μm across ten samples. Spatial analysis showed internal pores are regularly distributed, and though spacing was found to be largely independent of pore size, the variability in spacing was shown to be greater for smaller pores. Mechanical results show a strain-rate dependence and greater scatter at quasi-static rates, with the coefficient of variation for compressive strength and failure strain decreasing from 10.28% and 10.23% at quasi-static to 5.20% and 4.17% at dynamic rates. In view of the consistency demonstrated in the microstructure, the difference in variability between the quasi-static and dynamic mechanical properties is attributed to variability in testing conditions (e.g., misalignment of platens) and the activation of a greater number of pores in dynamic compression. In summary, these results motivate the use of new spatial characterization parameters via XCT for links to manufacturing, the integration of realistic microstructures into computational models, and focus on the role of defect distributions in dynamic compressive failure events.

View all citing articles on Scopus

View full text